When heating or cooling premises, it is necessary to establish a compromise between the comfort that is desired and the energy consumption that is necessary for achieving such comfort. Attempts at reducing energy consumption without sacrificing comfort have for a long time been directed to the thermal insulation of the premises. More recently, attempts have been made to control the inside temperature of the premises so as to maintain a desired degree of comfort by controlling a heater in such a manner as to cause such heater to operate for a minimum amount of time and/or at minimum power. In particular, attempts have been made to take into account the fact that the requirements of a user occupying premises in terms of quantity of heat to be supplied or removed vary from one day to another and even from one time of day to another, e.g. as a function of periods of non-occupation and/or of the alternation between day and night.
Since it is difficult, in general, to regulate the power of a heating device, proposals have been made to operate the heating device at full power but intermittently.
The oldest technique consists in fitting a heating device with a thermostat associated with a clock. Such a very rudimentary technique can achieve significant savings only at the cost of reduced comfort. Given the thermal inertia of the premises, obtaining a given comfort temperature after a period during which the heating device has been running low requires a period of "preheating" during which the heating device must operate at full power in order to bring the air in the premises gradually up to the comfort temperature (also referred to as the reference temperature).
Unfortunately, it is extremely difficult to determine the duration of the preheating period since it is a function of numerous parameters that are themselves difficult to determine or measure. If the preheating is too short, then there is a danger of the reference comfort temperature not being achieved at the desired time, whereas if preheating is too long, then there is wasteful consumption of energy.
Proposals have been made for an apparatus that switches a heating device on and off in compliance with a daily reference cycle that is fixed in advance. The cycle comprises two successive periods corresponding respectively to a low temperature (e.g. at night) and a comfortable temperature (by day). The preheating time that precedes the day or comfort temperature period is an empirical function of the inside and outside temperatures. This function is subsequently refined by iteration from one day to the next.
The above known apparatuses suffer from drawbacks.
For example, they require considerable computer infrastructure devoted solely to regulating heating. Consequently they are relatively expensive and unsuitable for domestic type applications, e.g. for heating an individual accommodation.
Further, there is no guarantee that the iteration process will converge, and this can affect reliability.
In addition, even assuming that the iteration does converge, it reaches a solution only after several iteration cycles, i.e. after several days. This gives rise to a loss of comfort and/or to wasted energy consumption.
Furthermore, such apparatuses are inflexible insofar as they are capable of operating only on the basis of a very simple daily reference cycle that, in most cases, comprises a single "comfort" period corresponding to a "comfortable" temperature (about 20.degree. C.), with the remainder of the cycle outside the comfort period corresponding to a lower temperature. Unfortunately, the requirements of an occupier of premises are generally more complex than that. As a result, apparatuses of the above type are not attractive for all users, in particular an individual accommodation or for small blocks of flats.
Finally, such known regulation apparatuses are unsuitable for combining with home controller systems installed in an individual accommodation to control other devices in the home, such as a security system or intercom etc., since they are not provided with appropriate communications interfaces for such home controller usage.